1. Field of the Invention
This invention relates to a laser apparatus and more particularly to a novel pulse laser apparatus provided with a pulse power source device of the DC-DC converter type.
2. Description of the Prior Art
Generally, as well known, gas laser apparatuses are arranged for bringing about a laser oscillation by impressing a high voltage on a laser discharge tube to excite a laser medium.
For such laser apparatuses, high voltage power sources of varied types have been used. One of these types is a power source device using a DC-DC converter. In the power source device of this type, a direct current on the primary side, i.e. the low voltage side, of a high frequency transformer is switched at a high speed by a switching element to generate a high voltage on the secondary side of the transformer. Then, the current is rectified and supplied to a laser discharge tube.
A power source of this type has an advantage that it obviates the necessity of the high voltage transformer of commercial frequency and a high voltage capacitor, etc. and thus permits substantial reduction in size of the laser apparatus.
Meanwhile, however, the laser apparatus with a power source of the conventional DC-DC converter type has a disadvantage that a high peak pulse laser beam cannot be produced in a stable manner.
In order to obtain a high peak pulse laser beam, therefore, it has been necessary to have recourse to a laser apparatus of the conventionally known gain switch type.
In the above stated gain switch type, a high tension resisting large current switching element such as a thyratron which is provided on the secondary side of a high voltage transformer is arranged to switch a high voltage current at a high speed to impress thereby a pulse voltage on a laser discharge tube. This gain switch laser type arrangement, however, has been teemed with shortcomings including: The laser apparatus becomes larger in size; use of a vacuum tube element such as a thyratron or the like is indispensable, whereby resulting in a short life of the apparatus; a long period of time is required for warm-up; heater power consumption lowers the overall efficiency of the apparatus; and so on. A further shortcoming resides in that the arrangement of this type does not permit setting a high voltage current at a desired value. This causes an excessively large current to flow to the gain switch and thus results in a low efficiency.